Trust me, it will start. It needs the compression to help created enough heat for combustion. If there is tightness coming from the tapered cylinder, this will go away after then engine is running and heats up. Sometimes a few drops of engine oil can help loosen it up too. Another thing I've done is put a few drops of oil in the cylinder and sit spinning the engine over by hand while watching TV or something; it does help a little.

Are you trying to spin it over by just grabbing the prop hub or do you have a prop on it? The prop will provide leverage, allowing you to spin it easier. Regardless, you should be able to flip start it with the prop on or use a good electric starter.